Triceratops may no longer have an
identity crisis. As paleontologists lock
horns on whether it was just a young
version of the larger Torosaurus, the
latest clues suggest the two were indeed
separate types.

A new study reveals immature and
adult examples of both Triceratops and
Torosaurus. “I don’t see any clear fossil
evidence that one dinosaur turned into
the other,” says Nicholas Longrich. He
and fellow Yale paleontologist Daniel
Field make their case online February
29 in PLoS ONE.

Comparisons between the dinos,
which both lived 65 million years ago
in western North America, start with
their skulls. Like many horned dinosaurs, Torosaurus sported a sizable frill
of bone perforated with two big holes.
Triceratops wore an unusually short and
solid crown.

Searching for adult Triceratops,

Skulls have been found of old and young
individuals for both Torosaurus (top)
and Triceratops (bottom), challenging
the claim that one dinosaur is merely
the younger version of the other.

Longrich and Field grouped 35 skulls
based mainly on how fused together the
bones were. Several Triceratops skulls
had completely fused, a sign of maturity
in modern animals. Some Torosaurus

skulls showed bones still joined by
sutures, which are hints of youth.

But fused bones may not be a reliableway to gauge age, says paleontologistJohn Horner of Montana State Univer-sity in Bozeman. “We recently collected100 new Triceratops specimens theyhaven’t seen,” he says. “We see a lot ofvariety in bone fusion.”In 2010 Horner blamed Triceratops’unusual frill on youth. Patches ofthinning bone on some skulls weresteps toward full-fledged holes and aTorosaurus adulthood, he and MontanaState colleague John Scannella argued.

Triceratops’ skull would have had
to change dramatically to achieve this
transformation. The depressions form
in different places than the holes.

Finding a skull halfway between existing specimens with small holes would
show that such remodeling is possible.
A transitional specimen matching this
description has been discovered, says
Horner. But Longrich and others believe
the strange skull in question — which
has no horn and extra holes in bizarre
places — belonged to a sick Triceratops or
another dinosaur called Nedoceratops.

Carnivores oftenlack sweet toothMutations in some speciesmean loss of taste for sugar

By Susan Milius

As a rough rule of tongue, animals that
have lost the power to taste sweetness
tend to be specialized meat-eaters.

give these carnivores much of an advantage as they hunt, speculates study
coauthor Gary Beauchamp of the Monell
Chemical Senses Center in Philadelphia.
So mutations in that sweet detector gene,
Tas1r2, could easily spread through
populations, Beauchamp and colleagues
propose in the March 27 Proceedings of
the National Academy of Sciences.

This loss isn’t universal among dedicated meat-eaters, though. Red wolves,
Canadian otters and aardwolves (hyena
relatives that stalk termites) turn out not
to have lost their genetic sweet spot. “Or
haven’t lost it yet,” Beauchamp says. Raccoons and spectacled bears, which eat
broader diets, also have intact genes to
taste sweetness, the researchers found.

Vegetarian animals such as the bam-boo-loving giant panda also can detectsweetness in their diet. Instead, the greatpanda has lost the ability to detect umami,the protein-related flavor of MSG.